This invention relates to circularly polarized antennas and more particularly to circularly polarized antennas for use in FM radio or in television broadcasting where the antennas are mounted on the top of a support tower and about a support mast which may be of conductive material.
Although horizontally polarized television broadcasting has been almost exclusively used in the United States, it appears from some recent test results, that circularly polarized broadcasting might well greatly improve television reception both in large metropolitan areas and in fringe areas.
This invention provides an antenna for broadcasting circularly polarized signals and which, when mounted on a support mast, radiates these signals in an omnidirectional pattern about the mast such that when this mast is erected in the center of a city, for example, substantially equal coverage is provided about the city. The problem of equal coverage about the mast becomes increasingly difficult with conventional antenna systems as the diameter of the mast becomes larger with attendant cloverleaf radiation patterns. These tower diameters tend to become fairly large if the tower supports many antenna systems for a plurality of broadcasters. The problem becomes increasingly difficult when this omnidirectional pattern is in the circularly polarized mode.